The most common cause of adult flatfoot is a problem with the posterior tibial tendon, one of the tendons in the foot.
Tendons connect muscles to bones and stretch across joints, enabling the joint to be bent. One of the most important tendons in the lower leg is the posterior tibial tendon, which starts in the calf, stretches down behind the inside of the ankle and attaches to bones in the middle of the foot. The posterior tibial tendon helps hold up the arch of the foot and provides support when stepping off the toes when walking.
If this tendon becomes inflamed, over-stretched or torn, the patient may experience pain on the inner ankle and gradually lose the inner arch on the bottom of the foot, leading to flatfoot. Signs and symptoms of posterior tibial tendon dysfunction include pain and swelling on the inside of the ankle, loss of the arch and the development of a flat foot. If left untreated, there will be gradually developing pain on the outer side of the ankle or foot, weakness and an inability to stand on the toes, and/or tenderness over the midfoot, especially when under stress during activity.
Posterior tibial tendon dysfunction often occurs in women over 50 years of age and may be due to an inherent abnormality of the tendon. Several other risk factors include: obesity, diabetes, hypertension, previous surgery or trauma (such as an ankle fracture on the inner side of the foot), local steroid injections, inflammatory diseases such as Reiter’s syndrome, rheumatoid arthritis, spondylosing arthropathy and psoriasis, among other conditions. Athletes who are involved in sports such as basketball, tennis, soccer or hockey may tear the posterior tibial tendon. The tendon may also become inflamed if excessive force is placed on the foot, such as when running on a banked track or road.
The diagnosis is based both on a history and a physical examination. As the condition progresses, the front of the affected foot will start to slide to the outside. From behind, it will look as though the patient has “too many toes” with the heel collapsing.
During the examination, the patient may be asked to stand on his or her toes or to do a single heel rise. Normally, the heel will rotate inward; the absence of this sign indicates posterior tibial tendon dysfunction. An ultrasound, X-rays and/or a magnetic resonance image (MRI) of the foot may be necessary in confirming the diagnosis.
Without treatment, the flatfoot that develops from posterior tibial tendon dysfunction may begin as a flexible problem (the joints still function properly) but then develop rigidity (the joints become stiff and arthritic). Pain may increase and spread to the outer side of the ankle because of the abnormal positioning of the bones. Gait may be affected and wearing shoes may be difficult.
Treatments depend on how far the condition has progressed. In the early stages, posterior tibial tendon dysfunction can be treated with rest, nonsteroidal anti-inflammatory drugs such as aspirin or ibuprofen, and immobilization of the foot for 6 to 8 weeks with a rigid below-knee cast or boot to prevent overuse. After the cast is removed, shoe inserts such as a heel wedge or arch support may be helpful.
If the condition is advanced, a custom-made ankle-foot orthosis or support may be necessary. If conservative treatments are unsuccessful, surgery may be necessary. Several procedures can be used to treat posterior tibial tendon dysfunction; often more than one procedure is performed at the same time, with the specific course of treatment based on each individual case.
Surgical options include:
- tenosynovectomy, a procedure in which the inflamed tissue surrounding the tendon is cleaned away (debrided) and removed (excised)
- osteotomy, a procedure to change the alignment of the heel bone (calcaneus)
- tendon transfer, a procedure that uses fibers from another tendon (the flexor digitorum longus, which helps bend the toes) to repair the damaged posterior tibial tendon
- lateral column lengthening, a procedure that involves placing a wedge-shaped piece of bone graft on the outside of the calcaneus which helps realign the bones and recreates the arch
- an arthrodesis procedure, which involves welding (fusing) one or more bones together, eliminating movement in the joint. This stabilizes the hindfoot and prevents the condition from progressing
Treatments are individualized based upon the degree of involvement of the foot as well as patient expectations. Dr. Vora is extensively experienced in the utilization of these techniques, has lectured and published on them and and has developed a model to study the condition and its associated treatments options. His goal during the correction of the flatfoot is maintaining and maximizing joint function whenever possible.
Modified from the AAOS